In pursuit of natural and uncoloured sound reproduction loudspeakers are generally designed to produce only the frequencies intended to be reproduced. This means that it is desirable to minimize secondary emissions stemming from the construction of the loudspeaker. As loudspeaker design does involve various practical compromises, elements of the speaker may have a tendency to exhibit natural oscillation in the sound frequency range of the loudspeaker, which deteriorates the pursued flat response. Accordingly, efforts have been made to control mechanical resonances of the vibrating diaphragm. One goal of diaphragm assembly design is therefore to avoid problematic resonances, called cone break-up modes, mainly in the operating frequencies of the diaphragm assembly or above it. Break-up above the operational frequency range show as deterioration of the distortion characteristics. In an attempt to eliminate excess noises, U.S. Pat. No. 8,804,996 B2 proposes to drive a stiffened diaphragm from the node of the first mode of vibration of the diaphragm.
While very effective, special stiffening structures are quite delicate to manufacture and to assemble onto a voice coil. It would, therefore, be desirable to provide a diaphragm assembly with good control over the mechanical resonances that would also be susceptible to automated manufacturing.